The paper presents progress in infrared (IR) detector technologies during 200 history of their development. Classification of two types of IR detectors (photon detectors and thermal detectors) is done on the basis of their principle of operation. The overview of IR systems and detectors is presented. Also recent progress in different IR technologies is described. Discussion is focused mainly on current and the most rapidly developing detectors: HgCdTe heterostructure photodiodes, quantum well AlGaAs/GaAs photoresistors, and thermal detectors. The outlook for near-future trends in IR technologies is also presented.

Infrared detectors: an overview

A real-time color image fusion system has been presented for the infrared thermal camera and the low-light-level camera,
which provides more complete spectral image information. The statistical transform method based on the YCRCBcolor model
transfers the first order statistics of the color distribution of a representative natural color daytime reference image to the false
color dual -band images. This mapping is usually performed in a perceptually decorrelated color space. The colors in the
resulting colorized dual-band images closely resemble the colors in the daytime color reference image. Also, object colors
remain invariant under panning operations and are independent of the scene content. Preliminary field trials demonstrate the
potential of these systems for applications like surveillance, security and target detection.

Real-time Color Image Fusion for Infrared and Low-light-level Cameras

This paper mainly examines the characteristics of magneto-optical (MO) images of weld defects under alternating and rotating magnetic field excitation. Weld defects including surface and subsurface defects were subjected to magneto-optical imaging (MOI) nondestructive testing (NDT) experiments. The MO images of different weld defects under alternating magnetic field excitation and rotating magnetic field excitation have been compared to determine the best effect of nondestructive testing, and a cruciform welding seam was used to verify the detection effect of rotating magnetic field. Besides, the values of standard deviation and maximum difference have been determined to analyze the difference in the effects of two magnetic fields, and image processing methods were applied to extract defect information, such as histogram equalization. Experimental results show that the optimal excitation voltage and lift-off value of rotating magnetic field are 120 V and 20 mm, respectively; image histogram equalization can significantly improve the contrast of MO images, and there is a distinct difference in the detection effect of two magnetic fields. Under the same excitation conditions, the detection effect of rotating magnetic fields is always better than the effect of alternating magnetic fields, and rotating magnetic field excitation has obvious advantages in detecting multidirection and subsurface defects in that the detection depth can reach about 8 mm.

Magneto-optical imaging characteristics of weld defects under alternating and rotating magnetic field excitation

This paper studies the magneto-optical image (obtained by different sampling frequencies) features of weld defects under alternating magnetic field excitation. Weld cracks with different gaps—0.03 mm, 0.05 mm, 0.07 mm, and 0.1 mm—were detected through the magneto-optical imaging method. In order to study the effect of sampling frequency on magneto-optical imaging, different sampling frequencies, such as 5 fps, 15 fps, 25 fps, 35 fps, 45 fps, 55 fps, 65 fps, and 75 fps, were used under the excitation of an alternating magnetic field. The distribution range of the gray-scale value for the magneto-optical image obtained at each sampling frequency was analyzed. The effect of the sampling frequency on the magneto-optical imaging was analyzed by comparing the magneto-optical images of weld defects and their gray-value curves at different sampling frequencies. Experimental results show that the sampling frequency of the magneto-optic sensor affects the distribution range of the gray-scale value of the magneto-optic image. Under the same experimental conditions, as the sampling frequency increases, the whole magneto-optical image becomes dark, and the span of the gray value becomes larger.

Influence of Sampling Frequency on Magneto-Optical Imaging Under Alternating Magnetic Field Excitation

In this paper, a novel x-ray imaging system was introduced. It was a CCD based system, but different from the traditional
CCD based x-ray imaging system, which was composed of the x-ray intensifying screen, the CCD and the low light level
image intensifier, specially using the zoom lens for coupling. Zoom lens can give a continuous variable visual field,
which not only reduce the geometrical blur but also can produce several image pairs for stereo imaging. It is convenient
for three dimension information extraction from a group of two dimension x-ray images and is valuable for stereovision
radiography in the application of medical diagnosis, security checking, non-destructive testing, and industry detection.
This stereo imaging method is also referential for the three dimension reconstruction daily living.

3D information extraction based on a novel x ray imaging system

Uncooled microbolometer infrared detectors are being developed for a wide range of thermal imaging applications. To design and manufacture high-performance microbolometer infrared detectors, numerical calculation and simulation is necessary. In this work, finite element methods are performed to simulate the transient temperature field of thermistor films of microbolometer infrared detectors. The varisized supporting legs' impacts on the performance of detectors are discussed. At the same time, variation of the bias voltage and the substrate temperature's impacts on total noise, noise equivalent to temperature difference (NETD) and detectivity (D*) are also discussed in details. These performance analyses are helpful for optimum design of microbolometer infrared detectors' structure and rational choice of working temperature of infrared focal plane arrays.

Performance analysis of low-cost uncooled microbolometer infrared detectors

A novel X-ray imaging system (NXRIS) and the design principles are given in this paper. Different from the existing digital X-ray imaging systems, the X-ray image intensifying system of NXRIS is a non-vacuum system composed of the intensifying screen and the brightness intensifier, and the brightness intensifier is named low light level image intensifier applied in military affairs. This structure makes NXRIS of big visual field (15 inch, even to larger) and low cost. When designing NXRIS, the spectral compatibility of the component devices and the relation between the visual field and the spatial resolution of the component devices are analyzed. The images produced by NXRIS are given and the image performance is good enough to be applied to security checking, non-destructive testing, and industry detection.

Design principles of a novel X-ray imaging system

By combining X-ray imaging technology and low light level imaging technology, the authors' research group designed the novel combined X-ray image intensifier. Different from the imported conventional one, it is an X-ray screen lens coupled with a brightness intensifier, and is a non-vacuum device. In this paper, the novel combined X-ray image intensifier is described in terms of its structure, imaging principle and imaging performance, and the comparisons of the structure, imaging principle and imaging performance between the novel combined one and the conventional one are given in detail. It is clear that the conventional medical tube is a little better than the novel combined one in imaging performance, whereas the novel combined one has a very high cost effectiveness and the satisfied imaging performance, and moreover, the quality disparity between the novel combined one and the imported medical one is being shortened. The novel combined one meets the X-ray imaging standard in many science and research fields and is convenient to be accepted by the usual users and has wide application fields such as industrial detection, nondestructive test and airport security check.

[The novel combined x-ray image intensifier].

Since x-ray was discovered and applied to the imaging technology, the x-ray imaging techniques have experienced
several improvements, from film-screen, x-ray image intensifier, CR to DR. To store and transmit the image information
conveniently, the digital imaging is necessary for the imaging techniques in medicine and biology. Usually as the
intensifying screen technique as for concerned, to get the digital image signals, the CCD was lens coupled directly to the
screen, but which suffers from a loss of x-ray signal and resulted in the poor x-ray image perfonnance. Therefore, to
improve the image performance, we joined the brightness intensifier, which, was named the Low Light Level (LLL)
image intensifier in military affairs, between the intensifying screen and the CCD and designed the novel x-ray imaging
system. This design method improved the image performance of the whole system thus decreased the x-ray dose.
Comparison between two systems with and without the brightness intensifier was given in detail in this paper. Moreover,
the main noise source of the image produced by the novel system was analyzed, and in this paper, the original images
produced by the novel x-ray imaging system and the processed images were given respectively. It was clear that the
image performance was satisfied and the x-ray imaging system can be used in security checking and many other
nondestructive checking fields.

A novel x-ray imaging system and its imaging performance

In the intelligent traffic system, the automatic recognition system of the car plate is an important development field. This system must satisfy the requirement of all-day long inspection. In the course of inspection, the lack of natural light(such as at night, in rainy day...) could be a problem, that is to say there could be backlighting problem, and this problem can be solved by using compensatory light. By now, the high-power floodlight has been adopted. Because of its own characteristics of the floodlight, the satisfied result cannot be obtained. In the present thesis, how to select the right light is analyzed, including car lights' spectra and visual response, and so on. The results of the practices are very satisfied. Language: zh

Chunyu Yu

Papers

Performance analysis of low-cost uncooled microbolometer infrared detectors

Design principles of a novel X-ray imaging system

[The novel combined x-ray image intensifier].

A novel x-ray imaging system and its imaging performance

The compensatory light for car plate recognition